The present invention relates to a mixer for any granular or particulate material of any granule or particle size, such a powders, grit-size material etc, which optionally may have liquids added thereto, as well as pastes, especially PVC paste. The mixer comprises a first mixing container portion that is pivotable about an axis positioned at an angle to the longitudinal axis of the mixing container portion and a second mixing container portion in which the mixed product, after separation from the first mixing container portion, is located for further use. The present invention also relates to a method for performing a mixing process in the inventive mixer.
Mixers having a mixing container consisting of two mixing container portions are known. In such mixers, the bottom mixing container portion into which the material to be mixed has been filled is connected to a second mixing container portion having a mixing tool and, subsequently, the mixing container is rotated by 180.degree. relative to a horizontal axis so that the mixing tool is now at the bottom. In this upside down position, in which the mixing tool rotates about a vertical rotary axis, the mixing process is performed. After completion of the mixing process, the mixing container is again rotated about the horizontal axis into its initial position in which the mixing container portion containing the mixed material can be separated from the other parts of the mixer.
From European Patent 0 269 799 B1 a mixing device is known in which a mixing container is provided comprised of two bowl-shaped mixing container portions that are connectable to one another. The mixer comprises a stationary holder at which one of the mixing container portions of the mixing container is rotatably supported so as to be pivotable about a horizontal support axis and wherein the second container portion has a mixing tool whose shaft in the mixing position is vertical.
In such mixers the mixing tool must be rotated at a high rpm in order to ensure that the material is sufficiently mixed. The material to be mixed is forced upwardly at the inner walls of the mixing container. This causes heating of the material to be mixed. This undesirable temperature increase is counteracted by cooling measures, for example, cooling of a double wall outer mantle of the mixing container. This requires a considerable additional expenditure, and may result in an undesirable change of the product properties because heating of the mixed material during mixing cannot be completely avoided.
It is therefore an object of the present invention to improve a mixer of the aforementioned kind such that an excellent mixing of the material can be performed in a short period of time without causing temperature-based undesirable changes of the material properties.